Control system.



K. A. SIMMON & A. J. HALL.

CONTROL SYSIEM.

"ammo" FILED APILE. I914.-

1,241,567. Patented 00a 2,1917.

Film" WITNESSES INVENTORS K W 5.- M-

7 AfTORNEY plurality of short-circuitlng switches,

pepvposition.

UNITED STATES PATENT OFFICE.

KARL A. SIMMON AND ARTHUR J. HALL, OF WILKINSBURG, PENNSYLVANIA, ASSIGN- ORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORA- TION OF PENNSYLVANIA.

CONTROL SYSTEM.

Specification of Letters Patent.

Patented Oct. 2, 1917.

Application filed April 6, 1914. Serial No. 830,098.

To all whom it may concern Be it known that we, KARL A. SIMMON, a citizen of the United States, and a resident of Wilkinsburg, in the county of Alleheny and State of Pennsylvania, and l hrrnUn J. HALL, a subject of the King of Great Britain, and a resident of Wilkinsbur in the count I of Allegheny and State of ennsylvania, ave invented a new and useful Improvement in Control Systems, of which the following is a specification.

Our invention relates to control systems, and it has special reference to systems of the type adapted to govern the operation of polyphase induction motors through the agency] of liquid rheostats.

One of the objects of our invention is to simplify and improve the operation and arrangement of circuits of a system of the above-indicated class and to provide effective and reliable means for short-circuiting the rheostat under predetermined conditions.

Another object of our invention is to provide a plurality of electrically operated switches for short-circuitin a liquid rheostat having a movable regu ating valve for fixing the level of the electrolyte, and to make provision for closing said switches under predetermined current conditions onl when the rheostat contains electrolyte and 'wlien the regulating valve occupies a predetermined position.

More specifically, the object of our invention is to provide a lurality of series relays'which are traversed by current pass-' ing through the rheostat and are adapted to act con ointl with an auxiliary switching device associated with the rheostat re ulating valve for efi'ectin the closure 0 a only when the regulating valve occupies its upper position, when electrol to is contained withm the rheostat, and w on the current traversing the rheostat is less than a predetermined amount.

In our co-pending application, Serial No. 830,096, filed of even date herewith, we have shown and described a control system of the general character hereinset forth, which embodies a. plurality of short-circuit ing switches that are operated when the rheostat regulating valve occupies its upith such a system, there is no assurance that the rheostat will be filled with electrolyte, even though the regulating valve is at its upper limit of travel, for the reason that, having initiated the automatic operation of the regulating valve, its movement will continue until the current traversing the rheostat and the current relay exceeds a predetermined amount. It is evident, therefore, that after once starting the automatic apparatus into action, the regulatable valve will be raised to its upper position, irrespective of whether or not the electrolyte supply system is operating properly.

Furthermore, there is a possibility that the short-circuiting switches would be closed under extremely severe operatin conditions and excessive load, which woul of course, be undesirable.

It is the purpose of our present invention to overcome the difiiculties hereinbefore mentioned and to provide adequate means for effecting reliable and safe operation.

Our invention may best be understood by reference to the accom anying drawing, the single figure of which is a diagrammatic view of a system of control embodying our invention.

Referring to the drawing, the system shown comprises a pluralit of supply-circuit conductors 1, 2 and 3 w ich are adapted to supply polyphase alternating current energy to primary windings 4 of an induction motor 5,.the secondary windings 6 of which are connected to a liquid rheostat 7 which is adapted to govern the operation thereof. A plurality of electrically operated line switches 10, 11 and 12 are interposed between the supply circuit conductors 1, 2 and 3 and the primary windings 4 of the motor 5, and are adapted to establish connections between them.

The liquid rheostat 7 comprises it containing tank 14 having a plurality of sets of cooperatin electrodes 15, 16 and 17, a. movable disc arge valve 18, and a movable regulating valve 19 for fixing the height of the electrolyte within the rheostat in the same general manner as set forth in the co-pending aipplication hereinbefore referred to. The ischarge valve 18 is actuated by a pneumatic device 21 of well-known construction, the operation of which is governed by an electrically controlled valve 22. A pneumatically operated dev'ce 24 is associated with the regulating valve I9 and is adapted to efi'ect its actuation. The device 24 is provided at its upper end with an electrically controlled valve 26 which is normally adapted to admit operating fluid from a suitable supply pipe 27 to the device 24, whereas its lower end is provided with an electrically controlled valve 28 which is normally closed and establishes a communication between the device 24 and the atmosphere.

This brief description of the operating mechanism of the liquid rheostat is deemed suflicient for present purposes, inasmuch as a full exposition thereof may be found by reference to the co-pending application :1]- ready .referred to.

The rheosta't 7 is further provided with an electrically operated inlet valve 30 for governing the admission of electrolyte there to, while an auxiliary interlocking switch 31 is associated with the operating device 24 and is adapted to be closed upon its cooperating terminals 31 when said regulating valve occupies its upper position.

Interposed in a conductor 33 between the secondary windings 6 of the induction motor 5 and the liquid rheostat 7, are a plurality of series relays or coils 34 and 35 which are respectively provided with movable switch members 36 and 37. The series relay 34 is so designed that, under no-load conditions, its associated switch member 36 is disengaged from its 006 crating stationary contact terminals 39, while the switch member 37 of the series relay 35 rests upon and engages its cooperating contact terminals 40, under similar conditions. The auxiliary interlocking switch 31 associated with the operating device 24, and the coi'iperating switch members of the series relays 34 and 35 act in conjunction to control the energizing circuit of a plurality of switches 43 and 44 which are adapted to establish short-circuit connections across the liquid rheostat.

The short-circuit switch 44 is provided with a movable interlocking switch segment 44" which is adapted to cooperatively engage a plurality of stationary contact terminals 44", 44 and 44". The switch segment 44 is adapted to occupy two positions, one marked Out which corresponds to the osition of the short-circuit switch 44 when it is deenergized, and the other marked In which corresponds to the closed position of the switch 44.

A master controller 49 is provided for governin the control circuits of the several electrically actuated devices, while a limit switch 50 is connected in circuit between the supply circuit conductor 3 and the primary windings 4 of the induction motor 5 and serves to effect an automatic operation of the rheostat 7.

Assuming the various circuit connections and apparatus to be as shown, the operation of the system is as follows; The master controller 49 is first moved to its position (1, thereby completing a circuit from the positive terminal of a battery 13, or other suitable source of energy, which includes the following apparatus, theseveral conductors being omitted for! simplification z-master controller 49, where the circuit divides, one branch traversing ,the energizing coils of the several line swi ches 10, 11 and 12, and thence to the negative terminal of the battery, another bran including the energizing coil of the electrically controlled discharge valve magnet 22 and thence to the negative terminal-of the battery, and another branch including the energizing coil of the inlet valve 30 to the negative terminal of the battery.

Thereupon, the line switches 10, 11 and 12 are closed to connect the motor 5 to the supply circuit conductors 1 2 and 3, while the discharge valve; 18 is closed and the inlet valve 30 is opened. Thus, electrolyte is per mitted to fill the rheostat 7 up to a level corresponding to the upper end of the regulating valve 19, as will be understood. At this level, the electrodes 17 are slightly imrnersed and, hence, the motor 5 is started into operation.

In order to bring the motor up to speed, the master controller 49 is moved to its sec.- ond /position b, in which a circuit is completed from the master controller 49 through the energizing coil of the electrically controlled valve 28 to the battery, while another circuit traverses the energizing coil of the electrically operated valve 26, and cooperating switch members 51 and 51" of the limit swltch 50 to the battery.

Upon the completion of the circuits just recited, the valve 28 is opened to admit operatin fluid to the lower end of the pneumatically operating device 24, while the valve 26 is closed to cut oil the operating fluid and permit its esca e to the atmosphere. Under these con itions, the operating device 24 moves the regulating valve 19 in an upward direction and thus permits a rise in the level of the electrolyte within the rheostat 7. The operation of the device 24 and its associated regulating valve 19 is controlled automatically by the current limit switch 50 which deenergizes the valve 26 whenever the motor current exceeds a predetermined value, as will be readily understood.

Without further description of the automatic operation, which is similar, in a general way, to many systems of the prior art, we shall assume that the regulating valve 19 has been raised to its upper position, in which the interlocking switch 31 engages its stationary contact terminals 31'. If, under these conditions, current traverses the liquid rheostat 7, which can only be done when it contains electrolyte, the relay 34 is raised to effect coiiperative engagement of its switch members 36 and 39, and if the current does not exceed a predetermined safe value for which the relay 35 is designed, cooperative engagement of its switch members 37 and 40 will be eifected.

Since our invention pertains directly. to this portion of the system, we will set forth the circuit connections in detail. Under the conditions just described, a circuit will be completed from the master controller 49 through conductor 54, cooperating interlock switch members 31 and 31", conductor 55, the relay 35, conductor 56, cooperating switch members 36 and 39 of the relay 34, conductor 57, cooperating contact terminals 44 and 44-which are bridged by the switch segment 44"by reason of the open position of the short-circuit switch 44, con doctor 58, energizing coils of the shortcircuit switches 43 and 44 and conductor 59 to the negative terminal of the battery B. The short-circuit switches 43 and 44 are, therefore, closed, and, in so doing, the in terlock switch member 44, associated with the short-circuit switch 44, transfers the energizing circuit from stationary contact terminal 44 to stationary contact terminal 44, which is connected to a holding circuit 60. Thus, after the short-circuit switches 43 and 44 are once closed, they are held in that position,irrespective of any subsequent action of the relays 34 and 35, and may be deenergized only by the lowering of the regulating valve 19 and the separation of interlock contact members 31 and 31.

In order to bring forth more clearl the functions of the relays 34 and 35, we esire to point out the possibility of an upward movement of the regulating valve 19 to its extreme position, even though the electrolyte circulating system be disabled and no electrolyte be admitted to the rheostat 7. It is, therefore, necessary to make provision against such a contingency which would otherwise result in short-circuiting the motor secondary windings ance had been excluded.

Furthermore, even though the electrolyte circulating system be operating properly and the regulating valve 19 occupies its upper position, it is possible that an extremely excessive current be traversing the rheostat, because of abnormal load or line conditions, which would render it undesirable to close the short-circuiting switches. Therefore, the relay 35 isprovided which acts conjointly with the relay 34 and interlocking switch 31 to permit the closure of the short-circuiting switches only when 6 before any resistthe current is within a predetermined safe value. y

the manner hereinbefore decoiiperating switch members 37 and 40 of scribed, the driving motor is thoroughly protected against misuse and injurious load conditions.

Modifications, of course, may be made in the arrangement of circuits and location of apparatus without departing from the spirit and scope of my invention, and such modifications are intended to becovered by the appended claims.

We claim as our invention:

1. The combination with translating means, a liquid rheostat having cooperating electrodes, means for admitting electrolyte into said rheostat, and means for short-circuiting said rheostat, of means for preventing the operation of said short-circuiting means until said rhcostat is filled with electrolyte and predetermined current conditions of said translating means are established.

2. The combination with a liquid rheostat having cotiperating electrodes, means for admitting electrolyte into said rheostat, and means for short-circuiting said rheostat, of means dependent upon predeter mined conditions of said rheostat and predetermined current conditions for governing the operation of said short-circuiting means.

3. The combination with a liquid rheostat having cooperating electrodes, means for admitting electrolyte into said rheostat,

and means 1 short-circuiting said rheostat, of means dependent upon electrolyte in said rheostat and upon the current traversing said rheostat for governing the op eration of said short-circuiting means.

4.. The combination with a liquid rheostat having cooperating electrodes, means for admitting electrolyte into said rheostat, and means for short-circuiting said rheostat, of a plurality of relays severally dependent upon the current traversing said rheostat for acting concurrently to govern the operation of said short-circuiting means.

5. The combination with a liquid rheostat havin co o'perating electrodes, means for admitting electrolyte into said rheostat, and means for short-circuiting said rheostat, of a plurality of relays respectively dependent upon diiferent'predeter,- mined currents traversing said rheostat for acting concurrently and conjointly to govcm the operation of said short-circuiting means.

6. The combination with a liquid rheostat having cooperating electrodes, means for admittin electrolyte into said rheostat, and means for short-circuiting said rheostat, of a plurality of relays respectively dependent upon current traversing said rheostat and upon a predetermined current traversing said rheostat for acting concurcircuiting means.

7. The combination with a liquid rheostat having cooperating electrodes, means for causing said rheostat to be filled with electrolyte, and electrically operated switches for short-circuiting said rheostat, of a plurality of relays in circuit with said rheostat and traversed by the rheostat current for conjointly controlling said shortcircuiting switches and preventing closure thereof until electrolyte is in said rheostat and the current is less than a predetermined amount.

8. The combination with a liquid rheostat, means for admitting electrolyte into said rheostat, a movable regulating valve for fixing the height of the electrolyte, and short-circuiting switches, of means associated with said re lating valve, and a plurality of relays or permitting closure of said short-circuiting switches only when the regulating valve is in its upper position, electrolyte is in the rheostat and the current traversing said rheostat is less than a predetermined value.

9. The combination with a liquid rheostat, means for admitting electrolyte into said rheostat a movable regulatable valve for fixing the height of the electrolyte, and electrically operated short-circuiting switches, of" automatic means for causing said short-circuiting switches to be closed only when the regulating valve occupies a predetermined position, when electrolyte is in said rheostat and when the current traversing said rheostat is less than a predetermined amount.

10. The combination with a liquid rheostat, means for admitting electrolyte into said rheostat, a movable re lating valve for fixing' the height of tl i: electrolyte, and electrically operated short-circuiting switches, of automatic means for closing said short-circuiting switches under predetermined current conditions when electrolyte is in said rheostat and the regulating valve occupies a predetermined position.

11. The combination with a liquid rheostat, means for admitting electrolyte into said rheostat, a movable regulating valve for fixing the height of the electrolyte, and electrically operated short-circuiting switches, of automatic means for closing said short-circuiting switches under predetermined current conditions when electrolyte is in said rheostat and the regulating uid rheo- 13. The combination with a liquid rheo- Y stat, and means for short-circuiting said rheostat, of a relays having different settings and severally dependent upon the current traversing said rheostat for acting concurrently to govern the operation of said short-circuiting means.

14. The combination with a liquid rheostat having cooperating electrodes, of means for regulating the depth of immersion of said electrodes, electrically-operated shortcircuiting switches for the electrodes, and automatic means for closing said switches under predetermined current conditions when said regulating means occupies a predetermined position.

15. The combination with a liquid rheostat, means for admitting electrolyte into the said rheostat, a movable regulating valve for fixing the height of the electrolyte, and electrically operated shortcircuiting switches, of a plurality of relays de pendent upon the current traversing said rheostat, one of which effects the engagement of its contact members when current traverses the rheostat, and the other effects the disengagement of its contact members underpredetermined circuit conditions, an auxiliary switch associated with said regulating valve and adapted to be closed in predetermined position thereof, and an energizing circuit for said short-circuiting switches interlocked through the contact members of said relays and through said auxiliary switc -In testimony whereof, we have hereunto subscribed our names this 31st day of March, 1914.

KARL A. SIMMON. ARTHUR J. HALL. Witnesses:

C. O. WHI'ITAKER,

B. B. Hnms. 

